GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"19549 results found.
- GRB 251106A: Swift/UVOT Upper Limits
- LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
- LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
- GRB 251102B: SVOM/GRM observation
- LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
- GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
- GRB 251106A: Swift-XRT afterglow detection
- GRB 251106A: Kilonova-Catcher optical upper limit
- GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
- GRB 251106A: MASTER optical observations
- GRB 251106A: SVOM detection of a burst
- EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
- GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
- GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
- GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
- GRB 251103B: Swift/UVOT Upper Limits
- LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
- GRB 251104A: SVOM detection of a burst
- GRB 251103A: WFST optical observations
- GRB 251103A: Xinglong 2.16m optical detection
- GRB 251103A: KAIT optical observations
- GRB 251103B: Nanshan/HMT optical upper limit
- GRB 251013C: 7DT detection and Medium-band SED of Afterglow
- GRB 251103B: MITSuME Akeno optical upper limits
- LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
- EP251102a: NIR observations with WINTER
- GRB 251103A: J-band detection with WINTER
- Swift GRB 251103B: Global MASTER-Net observations report
- GRB 251103B: GROWTH-India Telescope optical upper limits
- GRB 251103A: Kilonova-Catcher optical afterglow detection
- GRB 251103B: Enhanced Swift-XRT position
- GRB 251103B: Swift detection of a burst
- GRB 251103A: Swift/UVOT Detection
- GRB 251103A: Swift-XRT afterglow detection
- GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
- EP251102a: Einstein Probe detection of a fast X-ray transient
- EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
- GRB 251103A: LCO optical observation
- EP251102.890: COLIBRÍ optical counterpart candidate
- GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
- GRB 251103A: LCO optical afterglow detection
- GRB 251103A: NOT optical afterglow candidate
- GRB 251103A: SVOM detection of a bright burst
- GRB 251031A: Fermi GBM Observation
- LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
- GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
- GRB 251025C: SVOM/GRM observation
- GRB 251028A: SVOM/GRM observation
- GRB 251022A: Swift-XRT confirmation of fading
- GRB 251026A/EP251026a: SVOM/VT optical counterpart
- GRB 251028B: Fermi/GBM observation
- GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
- GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
- GRB251026B: PRIME H-band upper limit
- GRB251025B: 3.6m DOT Optical Observations
- SVOM trigger sb25102702/GRB 251027A is not a GRB
- GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
- GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
- EP251027.145: COLIBRÍ optical upper limits
- GRB 251022A: SVOM/GRM observation
- GRB 251026B: Swift ToO observations
- GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
- GRB 251027A: LCO optical upper limit
- GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251023B / EP251023b: Mondy optical upper limit
- GRB 251017A: INASAN-Kislovodsk optical observations
- GRB 251026A: Mondy optical upper limit
- GRB 251025B: Mondy optical observations
- GRB 251025B: Kilonova-Catcher optical afterglow detection
- GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
- GRB 251026B: Tentative GOTO optical counterpart candidate
- GRB 251025C: AstroSat CZTI detection
- EP251023a: Mondy optical observations
- GRB 251025B: MAO/AZT-22 optical observations
- LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
- GRB 251025B: J-band detection with WINTER
- GRB 251026A: SVOM/C-GFT upper limit
- IceCube-251025A: DDOTI Optical Upper Limit
- GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251026A: SVOM detection of a long burst
- GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
- GRB 251023A: SVOM/GRM observation
- GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
- GRB 251025B: GROWTH-India Telescope optical observations
- GRB 251024A: Swift/UVOT Upper Limits
- GRB 251025B: Swift-XRT afterglow detection
- GRB 251025A (sb25102501): stellar flare confirmed
- GRB 251025B: SVOM/VT optical observations with VHF data
- GRB 251025B: MASTER OT detection
- GRB 251025B: SVOM/C-GFT optical counterpart detection
- GRB 251025B: SVOM detection of a burst
- GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
- GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251025A: SVOM/VT VHF optical upper limit
- GRB 251025A: SVOM detection of a faint burst
- GRB 251024A: Enhanced Swift-XRT position
- GRB 251024A: LCOGT Optical Afterglow Detection
- GRB 251022A: KAIT optical observations
- GRB 251024A: Swift detection of a burst